Pulse power technology often needs very short, ultra-high power pulses. For example, certain light ion fusion experiments require pulses of 10-15 ns and 10.sup.13 -10.sup.14 W. These pulses could be attained with a fast opening switch of sufficient speed, current carrying capability and voltage hold-off capability, as power could be stored in inductors and released by the switch.
The first plasma-filled opening switch that could switch high power at a fast opening speed was reported by C. Mendel et al., "A fash-opening switch for use in REB diode experiments," Journal of Applied Physics, Vol. 48, No. 3, March 1977, page 1004. The switch uses an unconfined plasma to short out two spaced electrodes. When sufficient current flows through the switch, a sheath at the plasma-electrode interface begins to grow in thickness, increasing the impedance of the plasma gap. When this sheath is sufficiently thick, the diode current flows through the electrode rather than the plasma, and the switch is open. This plasma opening switch has been further developed since 1977, but it still has operational disadvantages such as difficulty in conducting currents for long times, strong dependence on the plasma parameters (making accurate timing difficult), and a reuqirement for high plasma densities for operation.
A triggered version of the switch, shown in applicant's copending application Ser. No. 884,858, filed July 14, 1986, now U.S. Pat. No. 4,727,298 overcomes the first two deficiencies listed above. However, this switch generally does use high plasma-fill densities and a trigger apparatus that may require space that is not readily available for some applications.